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Oct. 31, 1961 c. c. BROWN 3,006,413

PIPE STRIPPER FOR WELLHEADS Filed Jan. 10, 1958 2 Sheets-Sheet 1 C/ce/oC. .Brawn INVENTOR.

Oct. 31, 1961 c. (2. BROWN 3,006,413

PIPE STRIPPER FOR WELLHEADS Filed Jan. 10, 1958 2 Sheets-Sheet 2 F 26fll Z 3.5 2

C/cero C. 5/0 wn INVENTOR.

'14 T TOR/V5 Y 3,006,413 PIPE STRIPPER FOR WELLHEADS Cicero C. Brown,Brown Oil Tools Inc., P1). Box 19236, Houston, Tex. Filed Jan. 10, 1958,Ser. No. 708,170 Claims. (Cl. 166-82) This invention relates to wellheadequipment and particularly to improved pipe stripper and seal devicesfor use in wellheads.

In operation of oil and gas Wells, it is frequently necessary towithdraw the production pipe string, such as the conventional tubingstring, for replacement, repair, or for reworking of the well or partsof the well equipment. In order to safely withdraw such pipe string,means must ordinarily be provided to form a seal between the pipe stringbeing withdrawn and the surrounding casing or the wellhead through whichthe well pipe is withdrawn, in order to prevent blow-outs or loss ofcontrol of the well during the stripping operation.

Most pipe strippers employ a flexible resilient sealing sleeve throughwhich the pipe string is drawn in order to maintain a continuous sealbetween the withdrawn pipe and the surrounding pipe string or wellheadfitting, the seal means being such as will flex or expand suflicientlyto allow enlargements on the pipe strings, such as couplings and thelike, to be withdrawn through the stripping unit while the seal ismaintained about the moving string. Very often, high pressure conditionsare present or develop in the well bore during the course of thestripping operation and the seal elements are required to prevent escapeof such high pressure. The pressures encountered frequently are so highthat the sealing sleeve, which is usually rubber or similar resilientcomposition, may be blown out and release the pressure with attendanthazard to the well and personnel about the Well.

A primary object of the present invention is to provide an improved formof pipe stripper in which is incorporated metal re-enforcing elementsarranged to be expandible and contractible in accordance with thechanges in dimensions of the pipe string drawn therethrough, and whichwill act to re-enforce and support the sealing sleeve against thedestructive action of high pressures which may be encountered.

An important object is to provide a pipe stripper comprising a resilientsealing sleeve and an internal metal reenforcing core which willeffectively withstand high pressures and which is relatively simple inconstruction and easy to install on a wellhead.

Other and more specific objects and advantages of this invention willbecome more readily apparent from the detailed description when read inconjunction with the accompanying drawing which illustrates a usefulembodiment in accordance with this invention.

In the drawing:

FIG. 1 is a longitudinal view, partly in section and partly inelevation, of a pipe stripper device, showing the position of the partswhen contracted about the exterior of a pipe section;

FIG' 2 is a fragmentary view, similar to the upper portion of FIG. 1,showing the parts of the stripper and seal unit in their expandedpositions adapted to allow passage of an enlargement carried by the pipestring; and

FIG. 3 is a perspective view of the stripper unit from which the sealingsleeve has been removed to better illustrate the details of the internalmetal supporting core and re-enforcing elements thereof.

Referring to the drawing, there is shown a wellhead comprising the upperend of a well casing carrying a flanged wellhead fitting 11 at its upperend on which is mounted the tubular stripper housing 12 which carries atPatented Oct. 31, 1961 its lower end a flange 13 adapted to mate withflange 1'1 and to be bolted thereto in order to secure the stripperhousing to the wellhead. It will be understood that instead of theflange connections shown, the stripper housing 12 may be connecteddirectly to casing 10, by any other suitable and known type ofconnection fittings. Stripper housing 12 has side connections 14 and 15at intermediate points thereof for discharge or admission of fluids fromand into the bore of casing 10 as may be found necessary or desirableduring the course of operations. Shown extending through the bore ofcasing 10 and housing 12 is a pipe string, such as a tubing string,designated generally by the numeral 16, and comprising a plurality ofpipe sections 16a and 16b shown connected end-to-end by means of aconventional screw collar or coupling 17. The stripper and seal unit isshown positioned in housing 12 to form the stripper seal and betweentubing string 16 and bore 12a of the housing.

The stripper unit comprises a generally tubular sealing sleeve,designated generally by the numeral '18, constructed of flexibleresilient material, such as rubber and the like, disposed coaxially inhousing 12. Sleeve 18 comprises a substantially cylindrically straightshank portion 19 which merges into an inwardly tapering relative thicklip portion 20 defined by a generally conical inwardly tapering outerwall 21 and a similarly shaped inwardly tapering inner Wall 22. Innerand outer walls 22 and 21 are joined by a generally cylindrical walldefining a constricted bore 23 through lip portion 20 having a nominaldiameter slightly less than the external diameter of pipe 16 so as tonormally maintain slidable sealing engagement with the exterior of pipe16 as the latter is drawn through bore 23. The lower end of the walldefining bore 23 tapers outwardly to its juncture with the end of outerwall 21 to form the outwardly flaring surface 24 and providing a guidesurface for directing enlargements on pipe 16 into bore 23 of thesealing sleeve.

The opposite end of sleeve portion 19 is secured in any suitable manner,as by vulcanizing, to a metal ring 25 of generally rectangularcross-section, which projects radially slightly with respect to theexterior of sleeve 18 in order to be supportingly engaged on an upwardlyfacing annular shoulder 26 formed in the wall of bore 12a of thehousing, whereby to support the sealing sleeve against movement inwardlyof housing 12. Ring 25 has an annular packing groove 26a its outerperiphery and a packing 27 of any suitable form is disposed in groove26a to provide a fluid-tight seal between ring 25 and the bore wall ofhousing 12. Sleeve 18 is provided with a metal re-enforcing core whichincludes a tubular body 28 extending slidably into the outer end ofsleeve portion 19. The outer end of body 28 has a radially outwardlyextending annular flange 29 adapted to overlie ring 25. An annular cap30, having an axial opening 31 considerably larger in diameter than pipe16, is provided with internal threads 32 engageable with threads 33provided on the exterior of the upper end of housing 12 to permit thecap to be screwed down over the end of the housing. Cap 30 carries aninwardly extending annular lip 34 about its upper end defining opening31 and adapted to bear on the upper end of flange 29 so that when cap 30is screwed down over threads 33, lip 34 will be operative to clamp body28 and ring 25 down against shoulder 26 to thereby lock the stripperunit in place in the housing and prevent its displacement in eitherdirection from the bore of housing 12.

Body 28 carries about its inner end :margin a plurality of metal dogs orpawls 35 having T-shaped heads 36 at one end receivable incorrespondingly shaped T-slots 37 formed in the inner end margin of body28. The complementary shapes of the T-heads 36 and T-slots 37 are suchas to permit radial movement of pawls 35 without appreciable lateral orpivoting movement with respect to one another.

Each of the dogs or pawls 35 comprises a segment of a cylinder such thatwhen in their fully contracted position, as best seen in FIGS. 1 and 3,they will form a sub stantially closed continuous collar having aninternal diameter substantially equal to that of bore 23 and which isradially expandible and contractible. The free ends of pawls 35 aresloped inwardly to form generally conical faces 38 substantiallycomplementary to the slope of inner Walls 22 of the lip of the sealingsleeve and the outer peripheral surfaces of pawls 35 conform generallyto the configuration of the adjacent portions of the inner wall ofsleeve 18. The inner faces of the free ends of pawls 35 are shaped withoutwardly flaring end surfaces 39 merging with faces 38. The radialthickness of pawls 35 is such that they will be in continuouslymaintained contact both with the exterior of the tubing string and withthe inner wall of sleeve 18.

In operation, housing 12 carrying the stripper and seal unit locked inplace by cap 30, is positioned over the end of pipe string 16 andsecured to wellhead flange 11. As the pipe string 16 is drawn upwardlythrough the stripper structure, lip 20 of the sealing sleeve willclosely engage the exterior of the pipe string. Should any pressure develop in the annulus between pipe string 16 and casing 10, this pressurewill be exerted against the exterior of the sealing sleeve and will urgethe latter more tightly about the pipe. The external pressure on theseal sleeve will, of course, urge pawls 35 inwardly tightly about theexterior surface of pipe string 16 and because of their dimensions, thepawls will form a solid buttress ring which will effectively support theresilient material comprising the sealing sleeve and its lip portion soas to prevent any substantial degree of extrusion of the resilientmaterial along the pipe string which might destroy the sealing sleeveand its sealing function, if not thus prevented.

As the pipe string continues to be elevated and a coupling, such ascoupling 17, attempts to move through the sealing sleeve, surface 24will guide the coupling into bore 23 and the natural resilience of lip20 will permit bore 23 to expand sulficiently to allow the coupling topass through bore 23 and to then engage the outwardly flaring surfaces39 of the pawls, which will thereby be thrust radially outwardlysufliciently to allow coupling 17 to pass between the radially expandedpawls, as best seen in FIG. 2. At the same time, since pawls 35 will bethrust against the inner surface of sleeve portion 19, the latter willbe radially expanded snfliciently to allow the necessary outwardmovement of the pawls while at the same time will resiliently resistthis movement suflicient-ly to maintain the pawls in tight engagementabout coupling 17. The amount of the radial movement of the pawls willbe relatively small so that the interstices between the pawls will bequite small in width and too narrow to permit any substantial extrusionof the sealing sleeve through these narrow spaces. Ordinarily the numberof pawls 35 will be selected so that a minimum amount of separation willoccur as a result of the expansion required to allow passage of thecouplings or other conventional enlargements on the pipe string. In theembodiment illustrated, six pawls are shown, but it will be understoodthat a smaller or larger number of segments may be employed, dependingupon the degree of expansive movement expected and the pressures whichmay be anticipated during the operation of the device.

It will be understood that pipe connections may be made to fittings 14and 15 for relief of any pressure which may develop in the annular spacebetween the tubing and casing while the stripping operation takes place;or, if desired, weighting fluid may be introduced through these fittingsinto the casing to kill any pressure tending to cause a blowout.

It will be understood that various modifications and alterations may bemade in the details of the illustrative embodiment within the scope ofthe appended claims but without departing from the spirit of thisinvention.

What I claim and desire to secure by Letters Patent is:

1. A tubing stripper, comprising, a generally tubular housing mountableon a Wellhead, a flexible resilient sealing sleeve co-axially disposedin the bore of said housing, means securing one end of said sleeve influid-tight engagement to the housing, the opposite end of said sleevecomprising a generally conical portion tapering inwardly toward thelongitudinal axis of said sleeve and defining a constricted bore throughsaid portion adapted to provide slidable sealing engagement about theexterior of a pipe string being withdrawn therethrough, and a metalliccore means for reinforcing said sleeve, said core means com prising atubular body extending into the bore of said one end of said sleeve inclose fitting engagement therein, and a radially expandible andretractible metallic collar member secured to the inner end of said bodyand disposed inside the bore of the sleeve adjacent the interior of saidtapered end portion, said collar member comprising a plurality ofcomplementary arcuate segments, cooperating means on the inner end ofsaid body and the adjacent ends of said segments forming a radiallyslidable connection between the segments and said body, theconfiguration of the external periphery of said segments conformingsubstantially to that of the adjacent inner wall portions of saidsleeve, and the radial thickness of said segments being such as to havecontinuous contact with the exterior of said pipe string and with theinner wall of said sealing sleeve.

2. A tubing stripper according to claim 1 wherein said housing isprovided with fluid passage means opening radially through the wallthereof interiorly of the point of fluid-tight engagement of said sleeveto said housing.

3. A tubing stripper, comprising, a generally tubular housing mountableon a wellhead, a flexible resilient sealing sleeve coaxially disposed inthe bore of said housing, means securing one end of said sleeve influid-tight engagement to the housing, said means including an upwardlyfacing shoulder in the bore of the housing, a metallic ring secured tosaid one end of said sleeve and engageable on said shoulder, and meanson the housing for clamping the ring against said shoulder, the oppositeend of said sleeve comprising a generally conical portion taperinginwardly toward the longitudinal axis of said sleeve and defining aconstricted bore through said portion adapted to provide slidablesealing engagement about the exterior of a pipe string being Withdrawntherethrough, and a metallic core means for reinforcing said sleeve,said core means comprising a tubular body extending into the bore ofsaid one end of said sleeve in close fitting engagement therein, and aradially expandible and retractible metallic collar member secured tothe inner end of said body and disposed inside the bore of the sleeveadjacent the interior of said tapered end portion, said collar membercomprising a plurality of complementary arcuate segments, cooperatingmeans on the inner end of said body and the adjacent ends of saidsegments form-ing a radially slidable connection between said segmentsand said body, the configuration of the external periphery of saidsegments conforming substantially to that of the adjacent inner wallportions of said sleeve, and the radial thickness of said segments beingsuch as to have continuous contact with the exterior of said pipe stringand with the inner wall of said sealing sleeve.

4. A tubing stripper, comprising, a generally tubular housing mountableon a wellhead, a flexible resilient sealing sleeve coaxially disposed inthe bore of said housing, a metal ring secured to the outer end of thesleeve, an upwardly facing shoulder in the bore of the housingengageable beneath the ring to hold the sleeve against movement inwardlyof the housing, a tubular metal body extending into said outer end ofsaid sealing sleeve in close fitting engagement therein, the outer endof said body having an annular flange extending radially outwardly inoverlying engagement with said ring, means carried by the housing tourge said flange and ring into clamping engagement against saidshoulder, the opposite end of said sleeve comprising a generally conicallip portion tapering inwardly toward the longitudinal axis of saidsleeve and defining a constricted bore through said portion adapted toprovide slidable sealing engagement about the exterior of a pipe stringbeing withdrawn therethrough, a radially expandible and retractiblemetallic collar member secured to the inner end of said body anddisposed inside the bore of the sleeve adjacent the interior of saidtapered lip portion, said collar member comprising a plurality ofcomplementary arcuate segments, cooperating means on the inner end ofsaid body and the adjacent ends of said segments forming a radiallyslidable connection between the segments and said body, theconfiguration of the external periphery of said segments conformingsubstantially to that of the adjacent inner Wall portions of saidsleeve, and the radial thickness of said segments being such as to havecontinuous contact with the exterior of said pipe string and with theinner wall of said sealing sleeve.

5. A tubing stripper, comprising, a generally tubular housing mountableon a wellhead, a flexible resilient sealing sleeve coaxially disposed insaid housing and having one end secured in fluid-tight engagement to thehousing, the opposite end of said sleeve comprising a relatively thicklip portion defined by inner "and outer generally conical walls taperinginwardly toward the longit-udinal axis of said sleeve, the inner ends ofsaid walls being joined by a substantially cylindrical wall defining aconstricted bore through the lip portion adapted to provide slidablesealing engagement about the exterior of a pipe string being withdrawntherethrough, and a metallic core means for reinforcing said sleeve,said core means comprising a tubular body extending into the bore ofsaid one end of said sleeve in close fitting engagement therein, and aradially expandible and retractible metallic collar member secured tothe inner end of said body and disposed inside the bore of said sleeveadjacent the inner wall of said lip portion, said collar membercomprising a plurality of complementary arcuate segments, cooperatingmeans on the inner end of the body and the adjacent ends of saidsegments forming a radially slidable connection between the segments andsaid body, the configuration of the external periphery of said segmentsconfcrming substantially to that of the adjacent inner wall portions ofsaid sleeve, and the radial thickness of said segments being such as tohave continuous contact with the exterior of said pipe string and theinner wall of said sealing sleeve.

References Cited in the file of this patent UNITED STATES PATENTS2,096,882 Chernosky Oct. 26, 1937 2,163,007 ODell June 20, 19392,287,205 Stone June 23, 1942 2,555,647 King June 5, 1951 2,609,836 KnoxSept. 9, 1952 2,743,780 Brown May 1, 1956 2,762,638 Brown Sept. 11, 19562,808,229 Bauer et al. Oct. 1, 1957 2,832,617 Gibson Apr. 29, 1958

